Intended for healthcare professionals

Primary Care

Randomised equivalence trial comparing three month and six month follow up of patients with hypertension by family practitioners

BMJ 2004; 328 doi: (Published 22 January 2004) Cite this as: BMJ 2004;328:204
  1. Richard V Birtwhistle, professor of family medicine (birtwhis{at},
  2. Marshall S Godwin, professor of family medicine1,
  3. M Dianne Delva, associate professor of family medicine1,
  4. R Ian Casson, assistant professor of family medicine1,
  5. Miu Lam, associate professor of community health and epidemiology2,
  6. Susan E MacDonald, assistant professor of family medicine1,
  7. Rachelle Seguin, research associate1,
  8. Lucia Rühland, research associate1
  1. 1Centre for Studies in Primary Care, Queen's University, PO Bag 8888, Kingston, ON, Canada K7L 5E9
  2. 2Department of Community Health and Epidemiology, Queen's University, Kingston, ON, Canada K7L 3N6
  1. Correspondence to: R Birtwhistle
  • Accepted 26 November 2003


Objective To compare blood pressure control, satisfaction, and adherence to drug treatment in patients with treated hypertension followed up by their family physicians either every three months or every six months for three years.

Design Randomised equivalence clinical trial.

Settings 50 family practices in south eastern Ontario, Canada.

Participants 609 patients aged 30-74 years with essential hypertension receiving drug treatment whose hypertension had been controlled for at least three months before entry into the study.

Results 302 patients were randomly assigned to follow up every three months and 307 to follow up every six months. Baseline variables in the two groups were similar. As expected, patients in the six month group had significantly fewer visits, but patients in both groups visited their doctor more frequently than their assigned interval. Mean blood pressure was similar in the groups, as was control of hypertension. Patient satisfaction and adherence to treatment were similar in the groups. About 20% of patients in each group had blood pressures that were out of control during the study.

Conclusions Follow up of patients with treated essential hypertension every six months is equivalent to follow up every three months. Patient satisfaction and adherence to treatment are the same for these follow up intervals. As about 20% of patients'hypertension was out of control at any time during the study in both groups, the frequency of follow up may not the most important factor in the control of patients' hypertensionby family practitioners.


  • Contributors RVB, MSG, MDD, RIC, ML, SEM, and RS conceived and designed the study. RVB, MSG, RS, LR, and Jean Powers, Margaret Giles, and Xiaofang Ni collected the data, and all authors analysed and interpreted it. RVB, MSG, and ML drafted the article and all authors took part in the revision. RVB, MSG, MDD, RIC, ML, and SEM approved the version to be published. RVB is guarantor.

  • Funding Canadian Institute for Health Research; McKnight Fund of Queen's University.

  • Conflict of interest None.

  • Competing interest None declared.

  • Ethical approval Queen's University Research Ethics Board.

  • Accepted 26 November 2003
View Full Text